Lake Forest is a city located in Lake County, Illinois, United States. As of the 2010 census it had a population of 19,375. The city is along the shore of Lake Michigan, and is a part of the Chicago metropolitan area and the North Shore.

Lake Forest is an affluent city located in Lake County, Illinois, United States. The city is south of Waukegan, Illinois along the shore of Lake Michigan, and is a part of the Chicago metropolitan area and the North Shore.